49ers poised to sign veteran OLB Haggans

Clark Haggans had 14 sacks the past four seasons with the Cardinals. (AP)

First, the 49ers tried youth.

Now comes Plan B: experience.

The Niners will address their lack of depth at outside linebacker by signing 12-year veteran Clark Haggans, 35, a league source confirmed. The Sacramento Bee first reported the team’s interest in Haggans, whose four-year tenure with the Cardinals ended when Arizona released him Friday. Haggans’ signing is pending a physical.

The 49ers have just three outside linebackers on the roster in Aldon Smith, Ahmad Brooks and Parys Haralson, who has missed the past two practices. Haralson’s availability for the regular-season opener at Green Bay is unknown. Jim Harbaugh has said Haralson is “working through something,” his stock response when asked about an injured player. Will Haralson be available in Week 1? “We’ll see,” Harbaugh said Saturday.

The 49ers drafted two outside linebackers in April, but fifth-round pick Darius Fleming is on the PUP list after suffering an ACL tear in rookie minicamp. Seventh-rounder Cam Johnson underwent knee surgery in early June, missed the first three preseason games and was signed to the practice squad Saturday.

Haggans (6-4, 243), a fifth-round pick of the Steelers in 2000, would be the oldest non-specialist on the 49ers’ roster. He started all 16 games for the Cardinals last year and had 30 tackles and three sacks. He ranks 29th among active players with 46.5 career sacks.

The 49ers had just three outside linebackers on the roster last year in Smith, Brooks and Haralson. Their lack of depth was never an issue as that trio combined to play 54 of 54 games, including the playoffs.

The 49ers will need to release a player to make room for Haggans. They are carrying five safeties and four tight ends. Included among their quartet at tight end is Garrett Celek, the only undrafted rookie to make the 53-man roster.